<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<style charset='gb2312'>
table{
 width:280px;
margin: 0px;
padding: 5px;
border-width: 0;
border: 1px;
background-color: blanchedalmond;
text-align: center;
}
</style>
<body>
    <!-- 第一个单元格 -->
    <tr>
        <td colspan="4"><h3>促销计算器</h3></td>
    </tr>
    <!-- 第一个单元格 -->
    <tr>
        <td>商品单价</td>
        <td colspan="3"><input type="text" name="txtnum1" id="txtnum1"></td>
    </tr>
      <!-- 第一个单元格 -->
    <tr>
            <td>数量</td>
        <td colspan="3"><input type="text" name="txtnum2" id="txtnum2"></td>
    </tr>
    <tr>
        <td><input type="button" name="btn1" id="btn1" value="9折" ></td>
        <td><input type="button" name="btn1" id="btn1" value="9折" ></td>
        <td><input type="button" name="btn1" id="btn1" value="9折" ></td>
    </tr>
    <tr></tr>
</body>
</html>